A new CDC study has warned against couples rushing to get pregnant within two years of giving birth as they pose a high risk of conceiving a child with autism.
A gap of more than four years appears to be just as risky the researchers warn after assessing hundreds of US babies with developmental disorders.
According to the studies authors, women need at least 18 months to regain the healthy level of nutrients needed to carry and nourish a baby. Those who waited longer than average tended to have fertility issues.
The research adds further weight to current guidelines which advise waiting more than 18 months to conceive again to avoid premature births, low birth weight and placental abruption.
The study published today in the journal, Autism Research, is based on data from 356 children with autism spectrum disorder, 600 with developmental disorders, and 524 without any disorders.
The researchers found that overly-long or overly-short 'birth spacing' was directly correlated with autism, and not with any other disorder.
Short birth spacing is on the rise, according to data in the US and the UK.
For most women, fertility experts suspect, it could be due to women delaying their first pregnancies.
The CDC researchers, led by Dr Laura Schieve used data from the Study to Explore Early Development, a case-control study with rigorous case-finding the case-classification methods.
Dr Schieve, the leader author of the study, said: 'These findings support existing guidelines on pregnancy spacing and further highlight the association between autism and pregnancy health.
'Couples thinking about getting pregnant should discuss pregnancy planning with a trusted doctor or healthcare provider.'